1. Field of the Ivention
This invention relates to microphones.
2. Description of the Prior Art
Known microphones convert an analogue sound waveform (i.e. physical variations in air pressure) into an analogue electrical audio signal. If a digital audio signal is required, the analogue signal has to be converted by a digital to analogue converter (DAC) into the digital audio signal.
This extra stage of analogue to digital conversion requires extra components and, more importantly, is not a lossless process. In other words, some of the information contained in the original analogue audio signal is lost by the conversion process, through conversion errors or noise.
It would be desirable to provide a microphone which generates a digital audio signal directly from the air pressure variations representing the actual sound.
This invention provides a microphone comprising:
a diaphragm movable in response to incident sound waves;
a position sensor for generating an electrical position signal indicative of the position of the diaphragm;
a thresholder for generating a one-bit digital signal indicating whether the position signal is above or below a threshold signal level;
a delay for delaying the digital signal; and
a diaphragm driver for moving the diaphragm in response to the digital signal and in an opposite sense to the motion of the diaphragm represented by the digital signal.